Benadryl vs Nyquil

Benadryl vs Nyquil – detailed comparison:


It is the brand name of a medication called diphenhydramine, a first-generation antihistamine that is used to relieve symptoms of the common cold, allergy, and hay fever.


This medication is used to treat a variety of conditions, like – allergic symptoms, itchiness, insomnia (sleep problems), and motion sickness.


The usual recommended dose for adults is 50 mg four times a day. The usual recommended dose for children is 12.5 to 25 mg four times a day. The maximum recommended daily dose should not exceed 300 mg.

Side Effects And Precautions

Common side effects may include:

  • dizziness;
  • difficulty urinating;
  • dry mouth;
  • headaches.

Rare side effects may include:

  • erectile dysfunction;
  • painful urination;
  • excitement (particularly in children);
  • vision problems (particularly blurred vision);
  • constipation;
  • nervousness;
  • vomiting;
  • muscle weakness;
  • drowsiness;
  • increased chest congestion;
  • nausea;
  • unexplained weight loss;
  • loss of appetite.

Drug Interactions

It may negatively interact with other medications, especially:

  • opioid analgesics used to treat pain;
  • monoamine oxidase inhibitors (particularly if taken within the last 2 weeks);
  • drugs used to prevent migraines;
  • drugs used to treat heart conditions or hypertension;
  • medicines used to relieve anxiety;
  • drugs used to relieve stomach spasms or cramps;
  • medicines for sleep;
  • effient;
  • beta-blockers (metoprolol);
  • drugs used to help you relax;
  • keppra;
  • drugs that block the neurotransmitter acetylcholine, including some travel sickness drugs;
  • medicines used in Parkinson’s disease.


Drinking alcoholic beverages while taking this first-generation antihistamine increases the risk of side effects, therefore, avoid using alcohol while taking this medication.

Pregnancy & Breastfeeding

There are no well-done studies to determine the safe use of this first-generation antihistamine during pregnancy, hence, contact your doctor before using it if you are pregnant or plan to fall pregnant.

Additionally, it passes into the breastmilk, therefore, avoid this first-generation antihistamine if you are breastfeeding an infant.


It is a combination of dextromethorphan, doxylamine, and acetaminophen, which are used to treat sneezing, fever, headaches, cough, sore throat, and runny nose in children 12 years and older and adults.

Acetaminophen is a fever reducer and pain reliever. Dextromethorphan is a cough suppressant that affects the cough reflex in the brain that triggers coughing.

Doxylamine is an antihistamine medication that reduces the effects of the natural chemical histamine in the human body. Histamine can produce symptoms of itching, sneezing, watery eyes, and runny nose.


The medication is used to treat a cough, headaches, body aches, fever, itching, runny nose, sneezing, and watery eyes caused by allergies, the common cold, or the flu.


The usual recommended dose is 30 mL every 6 hours.

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Side Effects And Precautions

Common side effects may include:

  • dry eyes;
  • dry mouth or nose;
  • constipation;
  • sleep problems (insomnia);
  • upset stomach;
  • blurred vision;
  • trouble concentrating;
  • headaches;
  • mild dizziness;
  • feeling excited or restless (particularly in children);
  • drowsiness;
  • mild skin rash.

Less common side effects may include:

  • pounding heartbeat;
  • little or no urinating;
  • slow or shallow breathing;
  • seizure (convulsions);
  • unusual bleeding;
  • uneven heartbeats;
  • severe drowsiness;
  • severe headaches;
  • feeling light-headed;
  • restless muscle movements;
  • confusion;
  • tremor;
  • yellowing of the skin or eyes;
  • easy bruising;
  • dark urine;
  • hallucinations;
  • pain in the upper stomach;
  • pale skin;
  • loss of appetite;
  • clay-colored stools.

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Avoid drinking alcohol while taking this medication since it may increase your risk of liver damage and can increase the risk of other side effects.

To be sure that this medication is safe for you, tell your doctor if you have other medical conditions, especially:

  • liver disease;
  • glaucoma;
  • if you take potassium supplements;
  • a history of alcoholism;
  • bladder obstruction;
  • overactive thyroid;
  • heart disease;
  • if you take monoamine oxidase inhibitors;
  • coronary artery disease;
  • blockage in your digestive tract;
  • pheochromocytoma (tumor of the adrenal gland).

Drug Interactions

Tell your healthcare provider about all the drugs you use, and those you start or stop using during this treatment, especially:

  • non-steroidal anti-inflammatory drugs, such as – naproxen (Aleve), ibuprofen (Advil, Motrin), celecoxib, ketorolac, or diclofenac;
  • medicines used to prevent blood clots, such as – dalteparin, enoxaparin, desirudin, tinzaparin, or fondaparinux;
  • diuretics or “water pills”;
  • blood thinners, such as – warfarin.

Pregnancy & Breastfeeding

According to a 2016 study that was published in the journal JAMA Pediatrics, prenatal exposure to acetaminophen was strongly associated with an increased risk of behavioral problems in children, particularly when taken during the 3rd trimester of pregnancy.

Additionally, the medication is excreted in small quantities in breast milk and may negatively affect the infant. Thus, avoid this medication if you are breastfeeding a baby.

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Bottom Line – Benadryl vs Nyquil

Benadryl belongs to a group of drugs called Histamine H1 Antagonists. It works by blocking the effects of a substance released by the human body, called histamine, which is involved in allergies. It is mainly used to help reduce symptoms associated with allergies, such as – a runny nose and sneezing.

Nyquil is a combination medicine that is used to treat a headache, fever, cough, body aches, runny nose, sneezing, and sore throat caused by allergies, the common cold, or the flu.

In conclusion, both medicines are useful for treating allergy symptoms, however, both have plenty of side effects.

For instance, Nyquil contains alcohol and will cause liver damage if it becomes a habit. On the other hand, Benadryl has the active ingredient diphenhydramine and can strip your heart valves if it becomes a habit.

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